Pathogen derived resistance to Potato virus Y: Mechanisms and risks

Agricultural and Food Science in Finland

Volumn 8, Issue 4-5, 1999, Pages 493-513

  Mäki Valkama, Tuula ^b   Valkonen, Jari P T ^a  

^a SWEDISH UNIVERSITY OF AGRICULTURAL SCIENCES   (Sweden)

^b NONE

Author keywords

Genetic transformation; Solanum tuberosum; Transgenic plants; Virus resistance

Indexed keywords

EUKARYOTA; POTATO VIRUS Y; POTYVIRUS; SOLANUM TUBEROSUM; TUBEROSUM;

EID: 0033478807     PISSN: 12390992     EISSN: None     Source Type: Journal    
DOI: 10.23986/afsci.5643     Document Type: Review

References (174)

1. Aaziz, R. & Tepfer, M. 1999. Recombination in RNA viruses and in virus-resistant transgenic plants. Journal of General Virology 80: 1339-1346.
2. Al-Kaff, N.S., Covey, S.N., Kreike, M.M., Page, A.M., Pinder, R. & Dale, P.J. 1998. Transcriptional and post-transcriptional plant gene silencing in response to a pathogen. Science 279: 2113-2115.
3. Anandalakshmi, R., Pruss, G.J., Ge, X., Marathe, R., Mallory, A.C., Smith, T.H. & Vance, V.B. 1998. A viral suppressor of gene silencing in plants. Proceedings of the National Academy of Sciences USA 95: 13079-13084.
4. Andrejeva, J., Puurand, Ü., Merits, A., Rabenstein, F., Järvekülg, L. & Valkonen, J.P.T. 1999. Potyviral HC-Pro and CP proteins have coordinated functions in virus-host interactions, and the same CP motif affects virus transmission and accumulation. Journal of General Virology 80: 1133-1139.
5. Atabekov, J.G. & Taliansky, M.E. 1990. Expression of a plant virus-coded transport function by different viral genomes. Advances in Virus Research 38: 201-248.
6. Audy, P., Palukaitis, P., Slack, S.A. & Zaitlin, M. 1994. Replicase-mediated resistance to potato virus Y in transgenic tobacco plants. Molecular Plant-Microbe Interactions 7, 1:15-22.
7. Baulcombe, D.C. 1996a. RN A as a target and an initiator of post-transcriptional gene silencing in transgenic plants. Plant Molecular Biology 32: 79-88.
8. -1996b. Mechanism of pathogen-derived resistance to viruses in transgenic plants. The Plant Cell 8: 1833-1844.
9. -1999. Fast forward genetics based on virus-induced gene silencing. Current Opinions in Plant Biology 2: 109-113.
10. -& English, J.J. 1996. Ectopic pairing of homologous DNA and post-transcriptional gene silencing in transgenic plants. Current Opinion in Biotechnology 7: 173-180.
11. Beck, D.L., Dolleweerd, C.J. van, Lough, T.J., Balmori, E., Voot, D.M., Andersen, M.T., O'Brien, E.W. & Forsters, L.S. 1994. Disruption of virus movement confers broad-spectrum resistance against systemic infection by plant viruses with a triple gene block. Proceedings of the National Academy of Sciences USA 91: 10310-10314.
12. Beczner, L., Horvath, J., Romhanyi, I. & Förster, H. 1984. Studies on the etiology of tuber necrotic ringspot disease in potato. Potato Research 27: 339-352.
13. Benfey, P.N., Ren, L. & Chua, N.-H. 1989. The CaMV 35S enhancer contains at least two domains which can confer different developmental and tissue-specific expression patterns. EMBO Journal 8: 2195-2202.
14. -& Chua, N.-H. 1990. The cauliflower mosaic virus 35S promoter: combinatorial regulation of transcription in plants. Science 250: 959-966.
15. Borja, M., Rubio, T., Scholthof, H.B. & Jackson, A.O. 1999. Restoration of wild-type virus by double recombination of tombusvirus mutants with a host trasgene. Molecular Plant-Microbe Interactions 12, 2: 153-162.
16. SIO in potato. Theoretical and Applied Genetics 94: 198-203.
17. -, Voinnet, O., Li, W.-X., Ji, L.-H., Ding, S.-W. & Baulcombe, D.C. 1998. Viral pathogenicity determinants are suppressors of transgene silencing in Nicotiana benthamiana. EMBO Journal 17, 22: 6739-6746.
18. Carrington, J.C., Jensen, P.E. & Schaad, M.C. 1998. Genetic evidence for an essential role for potyvirus Cl protein in cell-to-cell movement. Plant Journal 14: 393-400.
19. Chachulska, A.M., Flis, B., Chrzanowska, M., Milner, M., Góra-Sochacka, A., Robaglia, C. & Zagórski, W. 1998. RNA -mediated potato virus Y resistance in potato and tobacco. 7th International Congress of Plant Pathology. Edinburg, Scotland 9-16 August 1998. Abstract no. 5.3.6.
20. Clark, W.G., Fitchen, J.H. & Beachy, R.N. 1995a. Studies of a coat protein -mediated resistance to TMV using mutant CP. I. The PM2 assembly defective mutant. Virology 208: 485-491.
21. -, Fitchen, J.H., Neijdat, A., Deom, C.M. & Beachy, R.N. 1995b. Studies of a coat protein -mediated resistance to tobacco mosaic virus (TMV). II. Challenge by a mutant with altered virion surface does not overcome resistance conferred by TMV coat protein. Journal of General Virology 76: 2613-2617.
22. Cogoni, C. & Macino, G. 1999. Gene silencing in Neurospora crassa requires a protein homologous to RNA-dependent RNA polymerase. Nature 399: 166-169.
23. Conner, A.J. & Dale, P.J. 1996. Reconsideration of pollen dispersal data from field trials of transgenic potatoes. Theoretical and Applied Genetics 92: 505-508.
24. Cooper, B., Lapidot, M., Heick, J.A., Dodds, J.A. & Beachy, R.N. 1995. A defective movement protein of TMV in transgenic plants confers resistance to multiple viruses whereas the functional analog increases susceptibility. Virology 206: 307-313.
25. Covey, S.N., Al-Kaff, V.S., Lángara, A. & Turner, D.S. 1997. Plants combat infection by gene silencing. Nature 385: 781-782.
26. Dale, P.J. 1992. Spread of engineered genes to wild relatives. Plant Physiology 100: 13-15.
27. de Carvalho, F., Gheysen, G., Kushnir, S., Montagu, M. van, Inzé, D. & Castresana, C. 1992. Suppression of ß-1,3 -glucanase transgene expression in homozygous plants. EMBO Journal 11: 2595-2602.
28. De Bokx, J.A. & Want, J.P.H. van der 1987. Viruses of Potatoes and Seed-Potato Production. PUDOC, Wageningen. 259 p.
29. -& Huttinga, H. 1981. Potato virus Y. CMI/AAB Description of Plant Viruses no. 242.
30. Dehio, C. & Schell, J. 1994. Identification of plant genetic loci involved in a post-transcriptional mechanism for meiotically reversible transgene silencing. Proceedings of the National Academy of Sciences USA 91: 5538-5542.
31. Dorlhac de Borne, F., Vincentz, M., Chupeau, Y. & Vaucheret, H. 1994. Cosuppression of nitrate reductase host genes and transgenes in transgenic tobacco plants. Molecular and General Genetics 243: 613-621.
32. Dougherty, W.G. & Parks, T.D. 1995. Transgenes and gene suppression: telling us something new? Current Opinion in Cell Biology 7: 399-405.
33. -, Lindbo, J.A., Smith, H.A., Parks, T.D., Swaney, S. & Proebsting, W.M. 1994. RNA-mediated virus resistance in transgenic plants: Exploitation of a cellular pathway possibly involved in RNA degradation. Molecular Plant-Microbe Interactions 7, 5: 544-552.
34. Eagles, R.M., Balmori-Melain, E., Beck, D.L., Gardner, R.C. & Forster, R.L.S. 1994. Characterization of NTPase, RNA-binding and RNA-helicase activities of the cytoplasmic inclusion protein of tamarillo mosaic potyvirus. European Journal of Biochemistry 224: 677-684.
35. Elmayan, T. & Vaucheret, H. 1996. Expression of single copies of a strongly expressed 35S transgene can be silenced post-transcriptionallly. Plant Journal 9, 6: 787-797.
36. English, J.J., Mueller, E. & Baulcombe, D.C. 1996. Suppression of virus accumulation in transgenic plants exhibiting silencing of nuclear genes. Plant Cell 8: 179-188.
37. Fang, G. & Grumet, R. 1993. Genetic engineering of potyvirus resistance using constructs derived from the zucchini yellow mosaic coat protein gene. Molecular Plant-Microbe Interactions 6, 3: 358-367.
38. Farinelli, L. & Malnoë, P. 1993. Coat protein gene-mediated resistance to potato virus Y in tobacco: Examination of the resistance mechanisms - Is the transgenic coat protein required for protection? Molecular Plant-Microbe Interactions 6, 3: 284-292.
39. N) in Solanum tuberosum cv. Bintje. Biotechnology 10: 1020-1025.
40. Fenczik, C.A., Padgett, H.S., Holt, C.A., Casper, S.J. & Beachy, R.N. 1995. Mutational analysis of the movement protein of odontoglossum ringspot virus to identify a host-range determinant. Molecular Plant-Microbe Interactions 8: 666-673.
41. Fujita, Y., Mise, K., Okuno, T., Ahlquist, P. & Furusawa, I. 1996. A single codon change in a conserved motif of a bromovirus movement protein gene confers compatibility with a new host. Virology 223: 283-291.
42. Gal, S., Pisan, B., Hohn, T., Grimsley, N. & Hohn, B. 1992. Agroinfection of transgenic plants leads to viable cauliflower mosaic virus by intermolecular recombination. Virology 187: 525-533.
43. Gerlach, W.G., Lleewelyn, D. & Haseloff, J. 1987. Construction of a plant disease resistance gene from the satellite RNA of tobacco ringspot virus. Nature 328: 802-805.
44. Golemboski, D.B., Lomonossoff, G.P. & Zaitlin, M. 1990. Plants transformed with a tobacco mosaic virus non-structural gene sequence are resistant to the virus. Proceedings of the National Academy of Sciences USA 87: 6311-6315.
45. Goodwin, J., Chapman, K., Swaney, S., Parks, T.D., Wernsman, E.A. & Dougherty, W.G. 1996. Genetic and biochemical dissection of transgenic RNA-mediated virus resistance. Plant Cell 8: 95-105.
46. Goy, P.A. & Duesing, J.H. 1996. Assessing the environmental impact of gene transfer to wild relatives. Biotechnology 14: 39-40.
47. Greene, A.E. & Allison, R.F. 1994. Recombination between viral RNA and transgenic plant transcripts. Science 263: 1423-1425.
48. -& Allison, R.F. 1996. Deletions in the 3 untranslated region of cowpea chlorotic mottle virus transgene reduce recovery of recombinant viruses in transgenic plants. Virology 225: 231-234.
49. Guo, H.S., Lopez-Moya, J.J. & Garcia, J.A. 1999. Mitotic stability of infection-induced resistance to plum pox potyvirus associated with transgene silencing and DNA methylation. Molecular Plant-Microbe Interactions 12: 103-111.
50. Haan, P. de, Gielen, J.J.L., Prins, M., Wijkamp, I.O., Schepen, A. van, Peters, D., Grinsven, M.Q.J.M. van & Goldbach, R. 1992. Characterization of RNA-mediated resistance to tomato spotted wilt virus in transgenic tobacco plants. Biotechnology 10: 1133-1137.
51. Hämäläinen, J.H., Watanabe, K.N., Valkonen, J.P.T., Arihara, A., Plaisted, R.L., Pehu, E., Miller, L. & Slack, S.A. 1997. Mapping and marker-assisted selection for a gene for extreme resistance to potato virus Y. Theoretical and Applied Genetics 94: 192-197.
52. -, Sorri, V.A., Watanabe, K.N., Gebhardt, C. & Valkonen, J.P.T. 1998. Molecular examination of a chromosome region that controls resistance to potato Y and A potyviruses in potato. Theoretical and Applied Genetics 96: 1036-1043.
53. Hämet-Ahti, L., Suominen, J., Ulvinen, T. & Uotila, P. (eds.). 1998. Retkeilykasvio. Yliopistopaino, Helsinki. 656 p.
54. Harrison, B.D., Mayo, M.A. & Baulcombe, D.C. 1987. Virus resistance in transgenic plants that express cucumber mosaic virus satellite RNA. Nature 328: 799-802.
55. N infection in three potato cultivars. Theoretical and Applied Genetics 94: 287-292.
56. Herskowitz, I. 1987. Functional inactivation of genes by dominant negative mutations. Nature 329: 219-222.
57. Heuvel, J.F.J.M. van den, Vlugt, R.A.A.van der, Verbeek, M., Haan, P.T. de & Huttinga, H. 1994. Characteristics of a resistance-breaking isolate of potato virus Y causing potato tuber necrotic ringspot disease. European Journal of Plant Pathology 100: 347-356.
58. Ingelbrecht, I., Houdt, H. van, Montagu, M. van & Depicker, A. 1994. Post-transcriptional silencing of reporter transgenes in tobacco correlates with DNA methylation. Proceedings of the National Academy of Sciences USA 91: 10502-10506.
59. Jacquet, C., Delecolle, B., Raccah, B., Lecoq, H., Dunez, J. & Ravalonandro, M. 1998. Use of modified plum pox virus coat protein genes develop to limit heteroencapsidation - associated risks in transgenic plants. Journal of General Virology 79: 1509-1517.
60. Jones, A.L., Johansen, I.E., Bean, S.J., Bach, I. & Maule, A.J. 1998. Specificity of the resistance to pea seed-borne mosaic potyvirus in transgenic peas expressing the viral replicase (NIb) gene. Journal of General Virology 79: 3129-3137.
61. Jones, R.A.C. 1990. Strain group specific and virus specific hypersensitive reactions to infection with potyviruses in potato cultivars. Annals of Applied Biology 117: 93-105.
62. Jorgensen, R.A., Que, Q. & Stam, M. 1999. Do unintended antisense transcripts contribute to sense cosuppression in plants? Trends in Genetics 15, 1: 11-12.
63. Kaniewski, W., Lawson, C., Sammoris, B., Haley, L., Hart, J., Dealnnay, X. & Tumer N.E. 1990. Field resistance of transgenic Russet Burbank potato to effects of infection by potato virus X and potato virus Y. Biotechnology 8: 750-754.
64. Kaplan, I.B., Shintaku, M.H., Li, Q., Zhang, L., Marsh, L.E. & Palukaitis, P. 1995. Complementation of virus movement in transgenic tobacco expressing the cucumber mosaic virus 3a gene. Virology 209: 188-199.
65. Kapteijns, A.J.A.M. 1993. Risk assessment of genetically modified crops, potential of four arable crops to hybridize with the wild flora. Euphytica 66: 145-149.
66. Karyeija, R.F., Gibson, R.W. & Valkonen, J.P.T. 1998. The significance of sweetpotato feathery mottle virus in subsistence sweet potato production in Africa. Plant Disease 82: 4-15.
67. Kasschau, K.D. & Carrington, J.C. 1998. A counterdefensive strategy of plant viruses: Suppression of post-trancriptional gene silencing. Cell 95: 461-470.
68. Kollar, A., Dalmay, T. & Burgyan, J. 1993. Defective interfering RNA-mediated resistance against cymbidium ringspot tombusvirus in transgenic plants. Virology 193: 313-318.
69. Krol, A.R. van der, Mur, L.A., Beld, M., Mol, J.N.M. & Stuitje, A.R. 1990. Flavonoid genes, in petunia: addition of a limited number of gene copies may lead to a suppression of gene expression. Plant Cell 2: 291-299.
70. Kumagai, M.H., Donson, J., Della-Cioppa, G., Harvey, D., Hanley, K. & Grill, L.K. 1995 Cytoplasmic inhibition of carotenoid biosynthesis with virus-derived RNA. Proceedings of the National Academy of Sciences USA 92: 1679-1683.
71. Kunz, C., Schöb, H., Stam, M., Kooter, J.M. & Meins, F. 1996. Developmentally regulated silencing and reactivation of tobacco chitinase transgene expression. Plant Journal 10, 3: 437-450.
72. Kurppa, A. 1983. Potato viruses in Finland and their identification. Journal of the Scientific Agricultural Society of Finland 55: 183-300.
73. Lapidot, M., Gafny, R., Ding, B., Wolf, S., Lucas, W.J. & Beachy, R.N. 1993. A dysfunctional movement protein of tobacco mosaic virus that partially modifies the plasmodesmata and limits virus spread in transgenic plants. Plant Journal 4, 6: 959-970.
74. Lawson, C., Kaniewski, W., Haley, L., Rozman, R., Newell, C., Sanders, P. & Tumer, N.E. 1990. Engineering resistance to mixed virus infection in an commercial potato cultivar: Resistance to potato virus X and potato virus Y in transgenic Russet Burbank. Biotechnology 8: 127-134.
75. Lecoq, H., Ravelonandro, M., Wiph-Scheibel, C., Monsion, M., Raccah, B. & Dunez, J. 1993. Aphid transmission of a non-aphid-transmissible strain of zucchini yellow mosaic potyvirus from transgenic plants expressing the capsid protein of plum pox potyvirus. Molecular Plant-Microbe Interactions 6, 3: 403-406.
76. -, Ravelonandro, M., Wiph-Scheibel, C., Monsion, M., Raccah, B. & Dunez, J. 1994. Significance of the heterologous encapsidation of zucchini yellow mosaic potyvirus in transgenic plants expressing plum pox potyvirus capsid protein. EPPO Bulletin 24: 555-559.
77. Li, H.-W., Lucy, A.P., Guo, H.-S., Li, W.-X., Ji, L.-H., Wong, S.-M. & Ding, S.-W. 1999. Strong host resistance targeted against a viral suppressor of the plant gene silencing defence mechanism. EMBO Journal 18: 2683-2691.
78. Lindbo, J.A. & Dougherty, W.G. 1992a. Pathogen-derived resistance to potyviruses: Immune and resistant phenotypes in transgenic tobacco expressing altered forms of a potyvirus coat protein nucleotide sequence. Molecular Plant-Microbe Interactions 5, 2: 144-153.
79. -& Dougherty, W.G. 1992b. Untranslatable transcripts of the tobacco etch virus coat protein gene sequence can interfere with tobacco etch virus replication in transgenic plants and protoplasts. Virology 189: 725-733.
80. -, Silva-Rosales, L., Proebsting, W.M. & Dougherty, W. 1993. Induction of a highly specific antiviral state in transgenic plants: Implications for regulation of gene expression and virus resistance. Plant Cell 5: 1749-1759.
81. Ling, K., Namba, S., Gonsalves, C., Slightom, J.L. & Gonsalves, D. 1991. Protection against detrimental effects of potyvirus infection in trasgenic tobacco plants expressing the papaya ringspot virus coat protein gene. Biotechnology 9: 752-758.
82. Lommel, S.A. & Xiong, Z. 1991. Reconstitution of a functional red clover necrotic mosaic virus by recombinational rescue of the cell-to-cell movement gene expressed in a transgenic plant. Journal of Cell Biochemistry 15A: 151.
83. Longstaff, M., Brigneti, G., Boccard, F., Chapman, S. & Baulcombe, D. 1993. Extreme resistance to potato virus X infection in plants expressing a modified component of the putative viral replicase. Embo Journal 12, 2: 379-386.
84. Lu, B., Stubbs, G. & Culver, J.N. 1998. Coat protein interactions involved in tobacco mosaic tobamovirus cross-protection. Virology 248: 188-198.
85. Mahajan, S., Dolja, V.V. & Carrington, J.C. 1996. Roles of the sequence encoding tobacco etch virus capsid protein in genome amplification: requirements for the translation process and a cis-acting element. Journal of Virology 70: 4370-4379.
86. Maia, I.G., Haenni, A.-L., & Bernardi, F. 1996. Potyviral HC-Pro: a multifunctional protein. Journal of General Virology 77: 1335-1341.
87. Maiti, I.B., Murphy, J.F., Shaw, J.G. & Hunt, A.G. 1993. Plants that express a potyvirus proteinase gene are resistant to virus infection. Proceedings of the National Academy of Sciences USA 90: 6110-6114.
88. Mäki-Valkama, T., Pehu, T., Santala, A., Valkonen, J.P.T., Koivu, K., Lehto, K. & Pehu, E. 1999. High level of resistance to potato virus Y by expressing P1 sequence in antisense orientation in transgenic potato. Molecular Breeding (in press).
89. Malnoë, P., Farinelli, L., Collet, G.F. & Reust, W. 1994. Small-scale field tests with transgenic potato, cv. Bintje, to test resistance to primary and secondary infections with potato virus Y. Plant Molecular Biology 25: 963-975.
90. Malyshenko, S.I., Kondakova, O.A., Nazarova, K.V., Kaplan, I.B., Taliansky, M.E. & Atabekov J.G. 1993. Reduction of tobacco mosaic virus accumulation in transgenic plants producing non-functional viral transport proteins. Journal of General Virology 74: 1149-1156.
91. McKinney, H.H. 1929. Mosaic diseases in the Canary Islands, West Africa and Gibraltar. Journal of Agricultural Research 39: 557-578.
92. Metzlaff, M., O'Dell, M., Cluster, P.D. & Flavell, R.B. 1997. RNA-mediated RNA degradation and chalcone synthetase A silencing in Petunia. Cell 88: 845-854.
93. Meyer, P., Heidmann, J. & Niedenhof, I. 1993. Differences in DNA-methylation are correlated with a paramutation phenomenon in trangenic petunia. Plant Journal 4: 89-100.
94. Montgomery, M.K. & Fire, A. 1998. Double-stranded RNA as a mediator in sequence-specific genetic silencing and co-suppression. Trends in Genetics 14, 7: 255-258.
95. Moreno, M., Bernal, J.J., Jiménez, I. & Rodriquez-Cerezo, E. 1998. Resistance in plants transformed with the P1 or P3 gene of tobacco vein mottling virus. Virology 79: 2819-2827.
96. Mueller, E., Gilbert, J., Davenport, G., Brigneti, G. & Baulcombe, D.C. 1995. Homology-dependent resistance: transgenic virus resistance in plants related to homology-dependent gene-silencing. Plant Journal 7, 6: 1001-1013.
97. Murphy, J., Rhoads, R., Hunt, A.G. & Shaw, J.G. 1990. The VPg of tobacco etch virus RNA is the 49 kDa proteinase or the N-terminal 24 kDa part of the proteinase. Virology 178: 285-288.
98. -, Rychlik, W., Rhoads, R.A., Hunt, A.G. & Shaw J.G. 1991. A tyrosine residue in the small nuclear inclusion protein of tobacco vein mottling virus links the VPg to the viral RNA. Journal of Virology 65: 511-513.
99. Namba, S., Ling, K., Gonsalves, C., Slightom, J.L. & Gonsalves, D. 1992. Protection of transgenic plants expressing the coat protein gene of watermelon mosaic virus II or zucchini yellow mosaic virus against six potyviruses. Phytopathology 82: 940-946.
100. Napoli, C., Lemieux, C. & Jorgensen, R. 1990. Introduction of a chimeric chalcone synthase gene into Petunia results in reversible co-suppression of homologous genes in trans. Plant Cell 2: 279-289.
101. Neuhuber, F., Park, Y.-D., Matzke, A.J.M. & Matzke, M.A. 1994. Susceptibility of transgene loci to homology-dependent gene silencing. Molecular and General Genetics 244: 230-241.
102. Nicolaisen, M., Johansen, E., Poulsen, G.B. & Bokhardt, B. 1992. The 5′ untranslated region from pea seed-borne mosaic potyvirus RNA as a translational enhancer in pea and tobacco protoplasts. FEBS Letters 303: 169-172.
103. N coat protein. Potato Research 39: 271-282.
104. Osbourn, J.K., Watts, J.W., Beachy, R.N. & Wilson, T.M.A. 1989. Evidence that nucleocapside disassembly and a later step in virus replication are inhibited in transgenic tobacco protoplasts expressing TMV coat protein. Virology 172: 370-373.
105. Palaqui, J.C., Elmayan, T., Pollien, J.-M. & Vaucheret, H. 1997. Systemic acquired silencing: transgene-specific post-transcriptional silencing is transmitted by grafting from silenced stocks to non-sielenced scions. EMBO Journal 16, 15: 4738-4745.
106. Pang, S.-Z., Slightom, J.L. & Gonsalves, D. 1993. Different meshanisms protect transgenic tobacco against tomato spotted wilt and impatiens necrotic spot Tospoviruses. Biotechnology 11: 819-824.
107. -, Jan, F.-J., Carney, K., Stout, J., Tricoli, D.M., Quemada, H.D. & Gonsalves, D. 1996. Post-transcriptional transgene silencing and consequent tospovirus resistance in transgenic lettuce are affected by transgene dosage and plant development. Plant Journal 9, 6: 899-909.
108. -, Jan, F.-J. & Gonsalves, D. 1997. Nontarget DNA sequences reduce the transgene length necessary for RNA-mediated tospovirus resistance in transgenic plants. Proceedings of the National Academy of Sciences USA 94: 8261-8266.
109. O. American Potato Journal 72: 523-532.
110. Powell-Abel, P., Nelson, R.S., De, B., Hoffmann, N., Rogers, S.G., Fraley, R.T. & Beachy, R.N. 1986. Delay of disease development in transgenic plants that express the tobacco mosaic virus coat protein gene. Science 232: 738-743.
111. Pringle, C.R. 1999. Virus taxonomy - 1999. Archives of Virology 144: 421-429.
112. Rajamäki, M.-L. & Valkonen, J.P.T. 1999. The 6K2 protein and VPg of Potato virus A are avirulence determinants associated with lack of systemic infection in Nicandra physaloides. Molecular Plant-Microbe Interactions 12: 1074-1081.
113. Ratcliff, F., Harrison, B.D. & Baulcombe, D.C. 1997. A similarity between viral defence and gene silencing in plants. Science 276: 1558-1560.
114. Ravelonandro, M., Monsion, M., Delpos, R. & Dunez J. 1993. Variable resistance to plum pox virus and potato virus Y infection in transgenic Nicotiana plants expressing plum pox virus coat protein. Plant Science 91: 157-169.
115. Reade, R., Wu, Z. & Rochon, D. 1999. Both RNA rear-rangement and point mutation contribute to repair of defective chimeric viral genomes to form functional hybrid viruses in plants. Virology 258: 217-231.
116. Register, J.C. & Beachy, R.N. 1988. Resistance to TMV in transgenic plants results from interference with an early event in infection. Virology 166: 524-532.
117. Reimann-Philipp, U. & Beachy, R.N. 1993. Coat protein -mediated resistance in transgenic tobacco expressing the tobacco mosaic virus coat protein from tissue-specific promoters. Molecular Plant-Microbe Interactions 6: 323-330.
118. Revers, F., Le Gall, O., Candresse, T., Le Romancer, M. & Dunez, J. 1996. Frequent occurrence of recombinant potyvirus isolates. Journal of General Virology 77: 1953-1965.
119. Riechmann, J.L., Laín, S. & Garcia, J.A. 1992. Highlights and prospects of potyvirus molecular biology. Journal of General Virology 73: 1-16.
120. Rochow, W.F. 1970. Barley yellow dwarf virus: Phenotypic mixing and vector specificity. Science 167: 875-878.
121. Rojas, M.R., Zerbini, F.M., Allison, R.F., Gilbertson, R.L. & Lucas, W.J. 1997. Capsid protein and helper component-proteinase function as potyvirus cell-to-cell movement proteins. Virology 237: 283-295.
122. Rokka, V.-M. 1998. Androgenic haploidization and interspecific and intraspecific somatic hybridization in potato germplasm development. PhD thesis. Department of Plant Production, University of Helsinki. 62 p.
123. Ross, H. 1986. Potato breeding - problems and perspectives. Journal of Plant Breeding. Supplement 13. 132 p.
124. Rubio, T., Borja, M., Scholthof, H.B. & Jackson, A.O. 1999. Recombination with host transgenes and effects on virus evolution: an overview and opinion. Molecular Plant-Microbe Interactions 12, 2: 87-92.
125. Ruibal-Mendieta, N.L. & Lints, F.A. 1998. Novel and transgenic food crops: overview of scientific versus public perception. Transgenic Research 7: 379-386.
126. Ruiz, M.T., Voinnet, O. & Baulcombe, D.C. 1998. Initiation and maintenance of virus-induced gene silencing. Plant Cell 10: 937-946.
127. Sanford, J.C. & Johnston, S.A. 1985. The consept of parasite-derived resistance: deriving resistance genes from parasite's own genome. Journal of Theoretical Biology 113: 395-405.
128. Sauli, J.O. 1941. Peruna. Yhteiskirjapaino. Helsinki. 126 p.
129. Schaad, M.C., Jensen, P.E. & Carrington, J.C. 1997. Formation of plant RNA virus replication complexes on membranes: role of an endoplasmic reticulum-targeted viral protein. EMBO Journal 16: 4049-4059.
130. Schiebel, W., Pelissier, T., Riedel, L., Thalmeir, S., Schiebel, R., Kempe, D., Lottspeich, F., Sänger, H.L. & Wassenegger, M. 1998. Isolation of an RNA-directed RNA polymerase-specific cDNA clone from tomato. Plant Cell 10: 2087-2101.
131. Schlüter, K., Fütterer, J. & Potrykus, I. 1995. "Horizontal" gene transfer from a transgenic potato line to a bacterial pathogen (Erwinia chrysanthemi) occurs - if at all - at an extremely low freaquency. Biotechnology 13: 1094-1098.
132. Schoelz, J.E. & Wintermantel, W.M. 1993. Expansion of viral host range through complementation and recombination in transgenic plants. Plant Cell 5: 1669-1679.
133. Selker, E.U. 1999. Gene silencing: repeats that count. Cell 97: 157-160.
134. Shahabuddin, M., Shaw, J.G. & Rhoads, R.E. 1988. Mapping of the tobacco vein mottling virus VPg cistron. Virology 163: 635-637.
135. Shukla, D.D., Colin, W.W. & Brunt, A.A. 1994. The Potyviridae. University Press, Cambridge, United Kindom, 516 p.
136. Sijen, T., Wellink, J., Hiriart, J.-B. & Kammen, A. van 1996. RNA-mediated virus resistance: Role of repeated transgenes and delineation of targeted regions. Plant Cell 8: 2277-2294.
137. Simon, A.E. & Bujarski, J.J. 1994. RNA-RNA recombination and evolution in virus-infected plants. Annual Review in Phytopathology 32: 337-362.
138. Simón-Buela, L., Guo, H.S. & García, J.A. (1997a). Long sequences in the 5′ noncoding region of plum pox virus are not necessary for viral infectivity but contribute to viral competitiveness and pathogenesis. Virology 233: 157-162.
139. Skogsmyr, I. 1994. Gene dispersal from transgenic potatoes to con-specifics: a field trial. Theoretical and Applied Genetics 88: 770-774.
140. Smith, H.A., Swaney, S.L., Parks, T.D., Wernsman, E.A. & Dougherty, W.G. 1994. Transgenic plant virus resistance mediated by untranslatable sense RNAs: Expression, regulation, and fate of nonessential RNAs. Plant Cell 6: 1441-1453.
141. -, Powers, H., Swaney, S., Brown, C. & Dougherty, W.G. 1995. Transgenic potato virus Y resistance in potato: Evidence for an RNA-mediated cellular response. Phytopathology 85: 864-870.
142. Sorri, V.A., Watanabe, K.N. & Valkonen, J.P.T. 1999. Predicted kinase 3a motif of a resistance gene analogue as a unique marker for potyvirus resistance. Theoretical and Applied Genetics 99: 164-170.
143. Stam, M., de Bruin, R., Kenter, S., Hoorn, R.A.L. van der, Blokland, R. van, Mol, J.N.M. & Kooter, J.M. 1997. Post-transcriptional silencing of chalcone synthase in Petunia by inverted repeats. Plant Journal 12, 1: 63-82.
144. Stanley, J., Frischmuth, T. & Ellwood, S. 1990. Defective viral DNA ameliorates symptoms of geminivirus infection in transgenic plants. Proceedings of the National Academy of Sciences USA 87: 6291-6295.
145. Stark, D. M. & Beachy, R.N. 1989. Protection against potyvirus infection in transgenic plants: Evidence for broad spectrum resistance. Biotechnology 7: 1257-1262.
146. Swaney, S., Powers, H., Goodwin, J., Silva-Rosales, L & Dougherty, W.G. 1995. RNA-mediated resistance with nonstructural genes from the tobacco etch virus genome. Molecular Plant-Microbe Interactions 8, 6: 1004-1011.
147. Tacke, E., Salamini, F. & Rohde, W. 1996. Genetic engineering of potato for broad-spectrum protection against virus infection. Nature Biotechnology 14: 1597-1601.
148. Taliansky, M.E., Ryabov, E.V. & Robinson, D.J. 1998. Two distinct mechanismis of transgenic resistance mediated by groundnut rosette virus satellite RNA sequences. Molecular Plant-Microbe Interactions 11, 5: 367-374.
149. Tanzer, M.M., Thompson, W.F., Law, M.D., Wernsman, E.A. & Uknes, S. 1997. Characterization of post-transcriptionally suppressed transgene expression that confers resistance to tobacco etch virus infection in tobacco. Plant Cell 9: 1411-1423.
150. Tapio, E., Bremer, K. & Valkonen, J.P.T. 1997. Viruses and their significance on agricultural and horticultural crops in Finland. Agricultural and Food Science in Finland 6: 323-336.
151. Tepher, M. 1993. Viral genes and transgenic plants. Biotechnology 11: 1125-1132.
152. Tiilikkala, K. 1987. Perunan Y -viroosin torjunta mineraaliöljyllä. M.S. Thesis, Department of Plant Pathology, University of Helsinki. 22 p. (In Finnish).
153. Valkonen, J.P.T. 1994. Natural genes and mechanisms of resistance to viruses in cultivated and wild potato species (Solanum spp.). Plant Breeding 112: 1-16.
154. -1998. Virus disease control in plants using natural and engineered resistance, and some considerations regarding biosafety. In: Current Issues in International Rural Development No. 17/18. SLU/Sida, Sweden, p. 51-55.
155. -& Mäkäräinen, E. 1993. Symptom expression and accumulation of potato virus Y (PVY-O) and potato leaf roll virus in thirteen potato cultivars. Agricultural Science in Finland 2: 33-40.
156. -& Palohuhta, J.P. 1996. Resistance to potato virus A and potato virus Y in potato cultivars grown in Finland. Agricultural and Food Science in Finland 5: 57-62.
157. -& Watanabe, K.N. 1999. Autonomous cell death, temperature-sensitivity and the genetic control associated with resistance to cucumber mosaic virus (CMV) in diploid potatoes (Solanum spp.). Theoretical and Applied Genetics 99: 996-1005.
158. -, Jones, R.A.C., Slack, S.A. & Watanabe, K.N. 1996. Resistance specificities to viruses in potato: standardization of nomenclature. Plant Breeding 115: 433-438.
159. Vance, V.B., Berger, P.H., Carrington, J.C., Hunt, A.G. & Shi, X.M. 1995. 5′ proximal potyviral sequences mediate potato virus X/potyviral synergistic disease in transgenic tobacco. Virology 206: 583-590.
160. Vardi, E., Sela, I., Edelbaum, O., Livneh, O., Kuznetsova, L. & Stram, Y. 1993. Plants transformed with a cistron of a potato virus Y protease (NIa) are resistant to virus infection. Proceedings of the National Academy of Sciences USA 90: 7513-7517.
161. Verchot, J. & Carrington, J.C. 1995. Evidence that the potyvirus P1 proteinase functions in trans as an accessory factor for genome amplification. Journal of Virology 69: 3668-3674.
162. -, Koonin, E.V. & Carrington J.C. 1991. The 35-kDa protein from the N-terminus of the potyviral polyprotein functions as a third virus-encoded proteinase. Virology 185: 527-535.
163. Vlugt, R. van der 1993. Engineered resistance against potato virus Y. Ph.D. Thesis. Agricultural University, Wageningen, the Netherlands. 111 p.
164. N coat protein gene are protected against PVY isolates and against aphid-mediated infection. Transgenic Research 2: 109-114.
165. N in tobacco plants transformed with the viral coat protein cistron. Plant Molecular Biology 20: 631-639.
166. -, Leunissen, J. & Goldbach, R. 1993. Taxonomic relationships between distinct potato virus Y isolates based on detailed comparison of the viral coat proteins and 3′-nontranslated regions. Archives of Virology 131: 361-375.
167. Voinnet, O., Vain, P., Angell, S. & Baulcombe, D.C. 1998. Systemic spread of sequence-specific transgene RNA degradation in plants is initiated by localized introduction of ectopic promotorless DNA. Cell 95: 177-187.
168. Wassenegger, M. & Pélissier, T. 1998. A model for RNA -mediated gene silencing in higher plants. Plant Molecular Biology 37: 349-362.
169. -& Pélissier, T. 1999. Signalling in gene silencing. Trends in Plant Science 4: 207-209.
170. Waterhouse, P.M., Graham, M.W. & Wang, M.-B. 1998. Virus resistance and gene silencing in plants can be induced by simultaneous expression of sense and antisense RNA. Proceedings of the National Academy of Sciences USA 95: 13959-13964.
171. Watterson, J.C. 1993. Development and breeding for resistance to pepper and tomato viruses. In: Kyle, M.M. (ed.). Resistance to Viral Diseases of Vegetables. Timber Press, Oregon, USA. p. 80-101.
172. Wefels, E., Salamini, F. & Rohde, W. 1993. Modification at the N-terminus of the potato virus Y capsid protein CP does not interfere with CP-mediated virus resistance in transgenic potato (Solanum tuberosum L.). Journal of Genetics and Breeding 47: 89-93.
173. Yamaya, J., Yoshioka, M., Meshi, T., Okada, Y. & Ohno, T. 1988. Cross protection in transgenic tobacco plants expressing a mild strain of tobacco mosaic virus. Molecular and General Genetics 215: 173-175.
174. Young, S.J.B., Woloshuk, S.L., Parry, D.C., Hellmann, G.M., Wernsman, E.A., Lommel, S.A. & Weissinger, A.K. 1995. Transgenic Burley and Flue-cured tobacco with resistance to four necrotic isolates of potato virus Y. Phytopathology 85: 1493-1499.